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Topic Review (Newest First)

07-16-2012 01:36 PM

CalebD

Re: Need an engine part that apparently doesnt exist anymore

If the castle nut wont work CapnBill's idea of having a prop shop modify your shaft for a newer prop attachment sounds good to me.

07-15-2012 08:39 PM

CapnBilll

Re: Need an engine part that apparently doesnt exist anymore

I had an old mercury engine with the same nut, I also lost it, and had to buy replacements, I bought a spare, but gave the whole thing away a few years ago. The castle nut doesn't work. How it was designed is s flat washer with ears that are bent into slots in the cone kept it from spinning. As you found out if the ears aren't bent well, (check them every time you go out), the prop spins off.

If no one has the old parts, a machine shop can fabricate one. Or you could have them modify the shaft for a newer and more secure prop attachment.

07-15-2012 07:32 PM

CalebD

Re: Need an engine part that apparently doesnt exist anymore

I'm with the Castle Nut crowd. Cheap, easy and solves your problem.
There could be a keyed insert (or keyway) OR a shear pin that hold the prop in position relative to the shaft.
The Castle Nut will just keep the prop from spinning off in reverse gear.
If you have a 1" shaft I have and old Castle Nut you could have for free.
Good luck.

07-15-2012 05:28 PM

travlineasy

Re: Need an engine part that apparently doesnt exist anymore

Quote:

Originally Posted by SloopJonB

Easier to get a thread gauge and measure what it is. They don't cost much and are very useful.

JonB, I'm pretty sure the nut is SAE thread, the engine was manufactured by Mercury early on, but I'm not sure who manufactured that particular model/year. Back in the early 1980s I had a marine store and worked on them, but that was a long time ago and I no longer have all the details stored in my aging head.

Good Luck,

Gary

07-15-2012 10:00 AM

JimsCAL

Re: Need an engine part that apparently doesnt exist anymore

Most small engines of that vintage have a shear pin that fits into slots in the conical nut and a cotter pin that hold the nut and prop on. The drawing you link to doesn't show the shear pin. Strange. Can't believe that with all the models that part is used on (through 1991), they don't carry carry it. Maybe there's a substitute. I would try talking to a local outboard repair shop. They may know what might work.

07-14-2012 03:38 PM

bandaidmd

Re: Need an engine part that apparently doesnt exist anymore

I don't know where your located(hint theres a profile spot where you put this info) but here's a place that sells used parts. Its located between the bay bridge and Easton in Maryland American Outboard Motors and Salvage

07-14-2012 01:44 PM

SloopJonB

Re: Need an engine part that apparently doesnt exist anymore

Quote:

Originally Posted by KBuckley

You also need to figure out whether it is imperial or metric so if you can bring the shaft with you when shopping that might be handy.

Easier to get a thread gauge and measure what it is. They don't cost much and are very useful.

07-14-2012 12:33 PM

travlineasy

Re: Need an engine part that apparently doesnt exist anymore

The prop is held in place by the shear-pin, and the shear pin is held in place by the back end of the prop hub. Take a close look at the back of the prop - you should see a slot cut in the back face of the prop. This is where the shear pin fits in place. When the nut is tightened, the shear pin is seated at the back of the prop. The castle nut is kept in place by the cotter pin that passes through the openings in the castle nut and also through the prop shaft.

Hope this helps,

Gary

07-14-2012 10:26 AM

Soundtrackzz

Re: Need an engine part that apparently doesnt exist anymore

It was my understanding the cone held the propeller onto the shaft, but apparently im wrong. The prop shaft is the only thing protruding outside of the gearhousing cap, so im going to guess that im missing a shear pin or something else that holds the propeller on

07-13-2012 08:31 PM

travlineasy

Re: Need an engine part that apparently doesnt exist anymore

If I recall correctly, the plastic cap on the back of the nut was nothing more than a decorative cone that was held in place with a cotter pin that went through a small hole the prop shaft. It really does nothing to enhance the performance or prevent cavitation. Just get an ordinary castle nut and some cotter pins to hold it in place when you shift to reverse.

Gary

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